This invention relates to patch radiator antennas and more particularly to patch radiator antennas wherein multiple patch radiators are used to control the direction of a beam of radio frequency (RF) energy from the antenna.
In missile applications, antennas are often required to be mounted conformally with the generally cylindrical shape of a missile. Antennas which adapt easily to conformal mounting usually produce a beam of RF energy having a main lobe directed normally (or broadside to) the missile. In fuzing applications, the required direction of the main lobe of the beam of RF energy is in a direction forward of the missile. To provide the latter, known patch antennas either include elements which are parasitically fed or corporate feeds to provide the RF energy to each patch element.
In a missile application, it is desirable to reduce the size and the cost of components in the missile including the fuze antennas. A fuze antenna needs to be inexpensive and typically a direct fed patch is the least expensive to fabricate because the feed and patch can be etched on a single layer in one step. One disadvantage with a direct fed patch is feedline radiation which contributes to co-polarized pattern interference and high cross-polarization levels. To minimize feedline radiation, the spacing to the ground plane can be decreased, but decreasing the ground plane spacing decreases the bandwidth of the patch. A desired antenna requires greater bandwidth while minimizing feedline radiation.
In a corporate feed for a patch array antenna, it is typically necessary to use resistors at coupler isolation ports and feedline terminations. Typically, resistors are soldered or welded to the circuitry to provide the requisite connection. Unfortunately, in high temperature applications, solder is unsuitable and welding requires touch labor and more complicated fabrication adding to the cost of the antenna.
RF connectors must also be connected to the circuitry to provide an appropriate connection to the antenna. Typically, RF connectors are soldered or welded to the circuitry to provide the requisite connection, but in high temperature applications, as stated above, solder is unsuitable and welding requires touch labor and more complicated fabrication adding to the cost of the antenna.